1. Field of the Invention
The present invention relates to a plasma display device using a surface discharge.
2. Description of the Related Art
A plasma display device having a large display capacity and exhibiting superior brightness, contrast, and viewing angle characteristics is widely noted as a flat panel display which can replace the cathode ray tube. The plasma display devices are divided into a direct current plasma display devices and an alternating current plasma display devices according to operating principles. In the direct-current plasma display device, all electrodes are exposed to a discharge space and charges move directly between the corresponding electrodes. Contrarily, in the alternating current plasma display device, at least one electrode among the corresponding electrodes is surrounded by a dielectric material and discharge occurs due to an electrical field of wall-charges.
FIGS. 1 and 2 show an example of a surface-discharge type plasma display device. Referring to the drawings, the plasma display device includes a rear substrate 10, first electrodes 11 formed on the rear substrate 10 in a predetermined pattern, a dielectric layer 12 coating on the first electrodes 11 and the rear substrate 10, a partition 13 on the dielectric layer 12, defining a discharge space and preventing electrical and optical crosstalk between neighboring discharge cells, and a front substrate 16 coupled to the partition 13, on the lower surface of which second and third electrodes 14 and 15 having a predetermined pattern perpendicular to the direction of the first electrode 11 are formed.
A dielectric layer 18 is formed on the lower surface of the front substrate 16 such that the electrodes 14 and 15 are embedded. A protective layer 19 can further be formed on the lower surface of the dielectric layer 18. A fluorescent layer 17 is formed at least one side of the discharge space defined by the partition 13. The discharge space is filled with a discharge gas.
In the plasma display device having the above structure, when a voltage is applied to the first electrode 11 and the second electrode 15, a common electrode, a preliminary discharge is generated between the first and second electrodes 11 and 15 and charged particles are formed on the lower surface of the dielectric layer 18 of the front substrate 16. In this state, as a predetermined voltage is applied between the second electrode 14 and the third electrode 15, a maintenance discharge is generated on the surface of the dielectric layer 18 of the front substrate 16. As a plasma is formed in a gas layer, ultraviolet light is emitted therefrom. The ultraviolet light excites fluorescent material of the fluorescent layer 17 and thus an image is formed.
However, the conventional plasma display device operating as above has problems as follows.
First, since the distance between the first and second electrodes is relatively wide, a high voltage, such as 300V, must be applied between the first and second electrodes to perform a preliminary discharge. This becomes the major cause of reduction in the life of a display panel.
Second, since the second and third electrodes are in the same plane, electrostatic capacitance between said second and third electrodes is relatively low and thus a plasma of weak energy is formed. Therefore, the brightness of an image deteriorates.
Third, since the second and third electrodes and the dielectric layer are formed on the front substrate, these electrodes should be formed of a transparent material. This not only limits the choice of materials for an electrode but also lowers the optical transmissivity of the front substrate.
And fourth, since the distance between the second and third electrodes is relatively narrow, in the maintenance discharge, the formation area of plasma is not wide so that the fluorescent material cannot be sufficiently excited.